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ACETONITRILE                                 79

small beaker. This distillate, on standing, almost completely
solidifies to a colourless crystalline mass. It is freed from
mother-liquor by spreading on a porous plate, and purified by a
second distillation. The acetamide has then a nearly constant
boiling-point. Yield, about 40 grams.
CH3.CO.ONH4 = CH3.CONH2 + H2O.
Properties.—Colourless, rhombohedral crystals, having a
peculiar smell of mice. This is due to impurity, which may be
removed by recrystallising from benzene ; m.p. 82°; b.p. 222° ;
easily soluble in water and alcohol.
Reaction,—l. Boil a small quantity of acetamide with caustic
soda solution. Ammonia is evolved, and sodium acetate is found                  |
in solution, CH3.CONH2 + NaOH = CH3.CO.ONa + NH3.
See Appendix) p. 243.
Acetonitrile (Methyl cyanide), CH3.CN.
Dumas, Malaguti and Leblanc, Annalen, 1848, 64, 332.
10 grms. acetamide
15     „     phosphorus pentoxide.
The phosphorus pentoxide is introduced into a small dis-
tilling flask (200 c.c.) attached to a short condenser. As the
pentoxide absorbs moisture rapidly and becomes sticky, it is
convenient to push the neck of the distilling flask through a
cork which fits the phosphorus pentoxide bottle, and then to
shake in the oxide until the required weight is obtained. The
powdered acetamide is immediately introduced and shaken up,
and the mixture distilled over a small flame, which is constantly
moved about. Add to the distillate about half its volume
of water, and then solid potassium carbonate, until no more
dissolves. The upper layer of liquid, which consists of methyl
cyanide, is separated and distilled over a little fresh phosphorus
pentoxide with thermometer. Yield, about 5 grams.
CH3.CO.NH2 - H2O = CH3CN.
Properties.—Colourless liquid with peculiar smell; b. p. 82°.
Reaction.—Boil a few grams of the acetonitrile with three